Chapter 13
Energy
 Ability of a physical system to do work
 Takes many forms
 Heat
 Chemical energy (stored in chemical bonds)
 Kinetic (energy of motion)
 Potential (stored)
Measuring energy
 Energy can be measured in
 kWh (kilowatt hour) measured by electric companies
 BTUs (British thermal units)
 Calories or joules (measures capacity of food to produce
heat);
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Calorie = kilocalorie (kcal) – measures potential energy in
food
1 Calorie = amount of heat required to raise 1 kilogram of
water by 1 degree Celcius
Basal metabolic rate
 Metabolic activities are physical and chemical
reactions in an organism that keep the organism alive
 Metabolism = to the sum of all metabolic activities
 BMR measures the energy required to sustain a
person’s metabolism for one day at complete rest
 BMR expressed in Calories
 BMR is influenced by
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Age, gender, height, body mass, body fat percentage
BMR
 Average adult of 150 lbs (68 kg) with body fat of 25%
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will have a BMR of 1500 Calories/day (at rest)
Typically require 20%-70% more Calories depending
on activity level
Boys ages 14-18 need 2400-2800 Calories / day
Girls ages 14-18 need 2000 Calories / day
Teenagers that are physically active need more
 Boys up to 3200 Calories / day
 Girls up to 2400 Calories / day
Nutrients
 Defined as substances the body needs for energy,
growth, and maintenance
 Water is a nutrient!!
 Macronutrients are carbohydrates, proteins, fats
 Essential nutrients are needed in small amounts
 Vitamins – carbon-based chemicals to help regulate
processes
 Minerals – elements required for good health
Carbohydrates
 Sugars (found in fruits and table sugar)
 Starches (found in pasta, grains)
 1 gram of carbohydrates produces 4 Calories of energy
 ½ of our energy should come from carbs
 but only 25% of the of carb calories should be from
sugars (sweets or sodas)
Proteins
 ¼ of our energy should come from proteins
 Made of amino acids (20 amino acids)
 9 are essential for adults and must come from diet
 12 are essential for children
 nonessential are produced in the body
 Proteins come from meats, legumes (beans, peas, soy),
and grains (rice, corn, wheat)
 1 gram protein produces 4 Calories of energy
Fats
 Lipids include solid fats and oils
 Contain different amounts of saturated and
unsaturated fatty acids
 Most saturated forms come from animal products
(meat and dairy) as well as some plants (coconut oil
and palm oil)
 High percentages of saturated or trans-fats are
unhealthy (causes heart disease)
Fats
 Unsaturated fats come from plant products
 Monounsaturated (canola, olive oils)
 Polyunsaturated (corn and soybean oils)
 Trans-unsaturated (artificially produced)
Fats
 1 gram of fat produces 9 Calories of energy
 Children between ages 4-18 obtain 25% - 35% of total
Calories from fats
 Should only be about 55.5 grams or 2 ounces / day
Vitamins
 Organic chemicals needed for normal metabolism
 Needed in small amounts
 Body produces insufficient amounts so most must
come through diet
 Fat soluble vitamins enter the body with lipids are can
be stored in adipose tissue
 Water soluble vitamins are not stored. Excess is
excreted with urine
Water-soluble vitamins
 Most are coenzymes (combines with a protein to make
a working enzyme)
 Can be used to catalyze reactions
 Include all B vitamins and C
 See table 13.6 (p. 457)
Fat-soluble vitamins
 Excess stored in adipose tissue and are not easily
excreted
 Can be toxic
 Include vitamins A, D, E, K
Minerals
 Elements needed in very small amounts but are
essential for normal functioning
 Considered a micronutrient (as are vitamins)
 Include Ca, F, I, Fe, Ph, K, Na
Minerals
 Calcium and phosphorous – components of bone
 Iron – helps RBCs transport oxygen
 Sodium – regulates water distribution and blood
pressure
 Recommended amounts = <1500 mg /day
 Most consume > 3400 mg /day due to high sodium
foods, processed foods, fast foods
 Increased Na leads to hypertension and heart disease
Alimentary canal
 Gastrointestinal tract – begins with the mouth and
ends with the anus
 Primary organs include: pharynx (throat), esophagus,
stomach, small intestine, and large intestine
 Accessory organs include: salivary glands, pancreas,
liver, gallbladder (connected to GI tract by ducts)
Activities of digestion
 Ingestion
 Taking in food involves mouth (teeth, lips, tongue)
 Propulsion
 Initiated by swallowing at pharynx and peristalsis
(contraction of muscles to push food down esophagus)
 Mechanical breakdown
 Breaking food down into smaller pieces to increase
surface area of food
 Chewing, churning of stomach, churning and
contractions in small intestine
Activities of digestion
 Chemical breakdown
 “digestion”
 Enzymes break large food molecules into small
molecules
 Absorption
 Movement of small molecules from small intestine into
blood
 Defecation
 Expulsion of non-digested / non-absorbed food
Layers of alimentary canal
 4 basic layers (see figure 13. 9, p. 462)
 Mucosa (mucous membrane)
 Innermost part is epithelial covered with mucous
 Areolar connective tissue (deeper) contains blood
vessels, lymphatic vessels, nerves, mucous-secreting
glands
 Submucosa
 Irregular, dense connective tissue with blood and
lymphatic vessels, nerves
 Secrete substances to aid digestion / absorption
Layers of alimentary canal
 Muscularis externa
 Two layers of smooth muscle
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Inner layer are circular
Outer layer are longitudinal
Layer of nerve fibers between them
 Propels food through the canal with peristalsis
 Aids with mechanical breakdown of food
Layers of alimentary canal
 Serosa (serous membrane) – minimizes friction
between organs and between organs and body wall
 In abdominopelvic cavity: peritoneum has two layers
 Parietal peritoneum lines the body wall
 Visceral peritoneum covers outside of the organs
 Connected to each other by mesentery (double layer of
peritoneum); holds organs in proper places
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Blood and lymphatic vessels travel in mesentery
 Space is the peritoneal cavity
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Filled with fluid to reduce friction
Oral cavity
 Aids with 4 of 6 digestion activities (ingestion,
mechanical breakdown, chemical breakdown,
propulsion)
 Lips
 Help ingestion by pulling food into mouth
 Keep food/drink from leaking out
 Voluntary control (skeletal muscle)
 Tongue
 Contain papillae for taste and gripping food
 Manipulates food for chewing a swallowing
Oral cavity
 Cheeks, hard palate, and soft palate form borders
within the oral cavity
Nasal cavity
 Passageway for air to enter and leave the nose
 Located above the palate
 Uvula prevents food from entering the nasal cavity
Teeth and gums
 Teeth – mechanical breakdown
 Gingiva – gums; soft tissue that covers necks of teeth
and maxilla and mandible
 Children have 20 deciduous teeth (begin to appear at 6
months are all present by 2 years)
 Adults have 32 permanent teeth (begin to come in at 6
years of age); 16 in maxilla and 16 in mandible
 Permanent teeth will push out the deciduous teeth
Deciduous teeth
Permanent teeth
Teeth (permanent)
 Incisors (front 4 teeth on top and bottom)
 Canines (lateral and posterior to incisors)
 Bicuspids (premolars); 2 on each side located between
canines and molars
 1st molars posterior to bicuspids
 2nd molars posterior to 1st molars
 3rd molars (wisdom) teeth don’t come in until late
teens early 20s (often removed)
Teeth
 Incisors – cutting
 Molars – crushing and grinding
 Canines – cutting
 Premolars – grinding and crushing
Tooth anatomy
 Crown – projects from the jawbone
 Coated with enamel (strongest material in body)
 Dentin located under the enamel
 Pulp cavity is hollow housing vessels and nerves
 Root – embedded in the jawbone
 Root canal passageway for nerves / vessels to reach pulp
cavity from jawbone
 Neck – between the root and crown
 Periodontal ligament holds each tooth in place
Salivary glands
 First accessory organs to aid in chemical digestion
 Located in oral cavity
 Secrete saliva via ducts
 Parotid glands (largest) lie under skin below and in
front of ears
 Submandibular glands lie on medial side of lower back
mandible
 Sublingual glands are on each side of the tongue
Salivary glands
Saliva
 Composed mostly of water, but also contains mucus,
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antibodies, enzymes
Water and mucus moisten food
Antibodies protect against infection
Amylase breaks down carbohydrates
Lipase begins breakdown of fats
Pharynx
 Connects mouth and nasal cavity to trachea and
esophagus
 3 main parts
 Nasopharynx – connects nasal cavity to oropharynx
(only air passes here)
 Oropharynx – food, liquids, air pass here (back of
mouth)
 Laryngopharynx – includes the glottis (opening to
trachea) and extends to esophagus
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Glottis is protected by epiglottis when swallowing so food only
goes into esophagus
Tonsils
 Bundles of lymphatic tissue that help prevent infection
Esophagus
 Muscular tube that connects the pharynx with the
stomach
 Posterior to trachea and heart
 Passes through opening in diaphragm
 Peristalsis pushes food down esophagus into stomach
Stomach
 Reservoir to break down food mechanically and
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chemically
Four parts: cardia (close to esophagus), fundus (upper
end), body (middle), pyloric region (lower end)
Lined with rugae (folds)
Wall has 3 layers of muscles (circular, longitudinal,
and oblique)
Pylorus opening between stomach and small intestine,
controlled by the pyloric sphincter
Stomach
Stomach lining
 Simple columnar epithelium (mucus-secreting cells)
 Contains gastric pits (of the gastric gland) that secret
gastric juice
 Cells lining gastric pits secrete mucus
 Cells of gastric gland (mucus-secreting, parietal, chief,
enteroendocrine)
 Parietal secrete HCl and intrinsic factor to absorb B12
 HCl kills bacteria activates pepsinogen to pepsin to break
down protein
 Chief cells secrete pepsinogen
 Enteroendocrine cells secrete more gastric juice
Chemical reactions of stomach
 Food in stomach mixes with gastric juice to form
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chyme
Contractions of wall keep mixing
Pepsin breaks down proteins
Intrinsic factor binds B12
Gastrin (and vagus nerve) release gastric juice and
continue churning motion
Pyloric sphincter relaxes to allow chyme to enter small
intestine
Small intestine
 Most chemical digestion occurs here
 All food absorption and most water absorption occurs
here
 Segments
 Duodenum
 1st and shortest segment; begins at pyloric sphincter
 Receives secretions from liver, gallbladder and pancreas
 Jejunum
 Follows duodenum
 Ileum
 Last segment
Small intestine
Lining of small intestine
 Surface area increased by circular folds that each have
villi and indentations or intestinal crypts
 Each villus has a lymphatic capillary (lacteal) and
blood capillaries and microvilli
Chemical breakdown in s.i.
 Chyme enters duodenum and mixes with bile and
pancreatic juice
 Bile – emulsification (breakdown of fats)
 Pancreatic juice has bicarbonate, amylase, lipase,
inactive proteases to breakdown chyme
 Bicarbonate – neutralizes acid
 Amylase – breaks down starches
 Lipase – breaks down lipids into fatty acids
 Proteases – become active in duodenum
Absorption in s.i.
 Large surface area of villi, intestinal folds, and microvilli
enhance absorption
 Monosaccharides→epithelial cells→blood capillaries
 Blood (from capillaries) moves into portal vein and goes to liver
 Fatty acids / monoglycerides→epithelial cells→packaged with
proteins to form chylomicrons→lacteals to combine with
lymph→enters blood
 Water and water-soluble vitamins absorbed
 Ileum has receptors for B12 + intrinsic factor
 Fat-soluble vitamins are absorbed with lipids
Liver and gallbladder
 Accessory organs
 Gallbladder stores bile and delivers it to duodenum as
needed
 Liver makes the bile which is used to breakdown lipids
 Liver is largest organ by weight and lies just under the
diaphragm; primarily on right side
Liver and gallbladder
Liver functions
 Maintain blood concentrations of glucose, lipids,
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amino acids
Convert nutrients to other forms
Synthesis and storage of glycogen
Secrete cholesterol, plasma proteins and clotting
factors
Store iron, lipids, fat-soluble vitamins
Absorption of and inactivation of toxins, hormones,
immunoglobulins (antibodies), drugs
Liver’s blood
 Hepatic artery delivers oxygen rich blood
 Hepatic vein drains the oxygen poor blood
 Deoxygenate / nutrient rich blood enters the liver via
hepatic portal vein then to liver capillaries
 Capillaries (sinusoids) are leaky due to fenestrations so
nutrients are easily diffused into hepatocytes
 Hepatic portal circulation makes it easier for the liver to
process / store nutrients
Liver lobules
 Functional units of the liver
 Each contains hepatocytes, blood vessels, bile
canaliculi and ducts that collect bile
Bile
 Watery solution containing bile salts (from
cholesterol)
 Bile salts emulsify fats to increase surface area and aid
their breakdown by lipases
 Bile is produced in hepatocytes, moved into canaliculi,
then to bile duct at triads
 Bile eventually ends up delivered to the duodenum
Bile storage
 Liver produces bile at steady rate.
 Bile is only needed after a meal.
 Bile is stored in the gallbladder where it becomes
concentrated.
Pancreas
 Accessory organ
 Serves as both and endocrine organ (secreting
substances into the blood) and an exocrine organ
(secreting substances into lumen of small intestine)
Pancreatic juices
 Secreted in inactive forms to prevent the self-digestion
of the pancreas
 Converted to the active forms of trypsin, chyotrypsin,
and carboxypeptidase in the duodenum
 Break down proteins
 Amylases break down starches
 Lipases break down lipids
Glucose regulation
 Beta cells of pancreas release insulin as a result of high
levels of glucose in the blood
 Insulin triggers hepatocytes in liver to take up more
glucose and store it as glycogen
 Insulin binding to adipocytes causes greater uptake of
glucose and its conversion to fat for storage
 Result is lower blood glucose levels
Glucose regulation
 Alpha cells release glucagon when blood glucose levels
are low
 Glucagon promotes the conversion of glycogen to
glucose in liver cells
 Glucose is then released into the blood
Large intestine
 Major segments: cecum, colon, rectum, anal canal
 Main functions are propulsion and elimination of
waste
 Additional / limited functions include absorption of
water, electrolytes, and vitamins
 Contains large colonies of bacteria which help produce
some B vitamins and vitamin K
 Not harmful but do produce gas
Cecum
 First part to receive food from small intestine
 Connects at ileocecal valve
 Appendix hangs off the lowest part of cecum; contains
lymphocytes to help prevent infections
 Appendicitis is usually caused by blockage,
inflammation, or other infection
Colon
 Four segments: ascending, transverse, descending,
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sigmoid
Ascending extends upward from cecum to right kidney
then turns 90 degrees
Now becomes the transverse colon; crosses from right
to left and turns down
Becoming descending colon then twists
Into the sigmoid colon that ends at the rectum
Rectum, anal canal, anus
 Anus is usually closed due to constriction of internal
and external sphincters
 Internal sphincter is smooth muscle
 External sphincter is skeletal muscle
 Defecation is elimination of solid waste
 Waste stretches the rectal wall to initiate the reflex of
muscle contractions
 Stimulates sphincters to relax allowing elimination to
occur
Homeostatic imbalance
 Gingivitis
 Inflammation of the gums
 Lead to periodontal disease (disease of tooth supporting
structures and tooth loss)
 Increases risk of heart disease
 Can be treated with professional teeth cleaning and
improved oral hygeine
Homeostatic imbalance
 Gastroesophageal reflux disease (GERD)
 Movement of chyme from stomach into lower esophagus
 Painful burning (heartburn)
 Can cause chronic inflammation (GERD)
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Due to pregnancy
Hiatal hernia (part of stomach protrudes through diaphragm)
Treatment includes smaller meals more frequently; avoid
eating before bedtime; surgery
Homeostatic imbalance
 Ulcers (peptic ulcers)
 Break in protective lining of stomach, duodenum, or
lower esophagus
 Most caused by infection from Helicobactor pylori
 Treatment includes antibiotics, drugs to slow acid
production
Homeostatic imbalance
 Gastroenteritis
 Inflammation of stomach or intestine
 Nausea, vomiting, diarrhea, abdominal pain
 Is contagious and typically caused by rotavirus
 Treatment is hydration and replacement of lost
electrolytes
Homeostatic imbalance
 Inflammatory Bowel disease
 Inflammation of intestines
 Diarrhea and pain; cause not clear
 Ulcerative colitis
 Affects only colon and mucosal layer of intestine
 Crohn’s disease
 Affect all four layers of intestinal tract
 All forms can suffer malabsorption, pain, weight loss
 Treatment includes steroids to reduce inflammation,
lifestyle changes with diet (reduce fiber)
Homeostatic imbalance
 Constipation
 Waste spends too much time in colon; no longer
contains enough water and becomes very solid
 Causes include weak muscles, lack of fiber, lack of
exercise, some medications
 Diarrhea
 Waste still contains too much water
 Causes include dysentery, food poisoning, bowel
disease, milk consumption when lactose intolerant
Homeostatic imbalance
 Hepatitis
 Inflammation and damage to the liver
 Caused by viral infection (A-E), alcohol or drug
consumption, poisoning
 Acute hepatitis (less than 6 months) can allow liver to
heal but can lead to liver damage and death
 Chronic hepatitis is less severe but lasts longer than 6
months
 Common symptom is jaundice, lack of blood clotting
 Prevention: proper hygiene and vaccines (for A and B)
Homeostatic imbalance
 Pancreatitis
 Inflammation of the pancreas
 Enzymes become active inside the pancreas
 Severe abdominal pain
 In US linked to alcoholism
 Can result from gallstones
Homeostatic imbalance
 Gallstones
 Solid crystals formed in the bile in the gallbladder
 Typically get stuck in a duct creating a blockage
 Pain and inability to digest fats
 Treatment: cholecystectomy (removal of gallbladder)
and less fatty meals
Homeostatic imbalance
 Cancer
 Most common forms and deadliest
 Typically not detected until they enter other body
tissues
 Screening and early detection are key to survival